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Refrigerated Adsorption Dehumidified Drier for Agri products

An innovative Refrigeration Adsorption Dehumidification Drying (RADD) solution. The idea was to lower the humidity in the drying chamber, thereby facilitating higher mass transfer rates from the spice such as nutmeg, cardamom (elachi) while the drying process. Humid air from the drier room, at about 600 C, is passed through a finned tube heat exchanger, where it is partially cooled and sent to the evaporator of a refrigeration system. Heat exchange between the refrigerant and the partially cooled, humid air results in cooling below the dew point, as a result, the moisture in the air gets condensed as liquid water. The condensed water is removed from the system. While condensing, the latent heat of condensation, as well as the sensible heat is transferred to the refrigerant. In certain cases, dehumidified air is further dehumidified using a silica gel adsorber and then sent to the shell side of the finned tube (FT) heat exchanger, where it exchanges heat with the hot incoming air from the drier room. Meanwhile, the refrigerant coming out of the evaporator is compressed while the heat of compression is removed in the condenser by exchanging heat with the air to be recycled to heat up the air. The resultant dehumidified hot air is pumped back to the drier room for the drying operation……

RADD_Dryer_for_drying_vegetables_and_exotic_spices.pdf (327.4 KiB, 231 hits)

Quantified Impact achieved and targeted

  • Shelf life enhancement of agri produces through low-temperature drying
  • Totally a green process and no environmental related issues
  • Since the energy is conserved, the process is cost-effective compared to conventional drying methods
  • Suitable for most of the common agri crops for value addition
  • Scalable up to 2 TPD capacity

Salient Technical Features

  1. Dehydration Process for the production of superior quality of spices like nutmeg, cardamom, etc. for maximum retention of colour, flavour and free from aflatoxins
  2. Since the air is recycled back into the drier room rather than venting it out to the atmosphere, energy is conserved
  3. The system operates automatically and no manpower is required for the firing of fuel or for hot air generation.
  4. Multipurpose drier through which a variety of heat-sensitive materials like spices, fruits, vegetables, flowers, medicinal plants and leaves could be dried without affecting the quality and these were demonstrated